Video transmission method, video reception method, video transmission apparatus, and video reception apparatus

ABSTRACT

A video transmission method according to the present disclosure includes: generating a transmission signal including, in a time series, first video data having a first luminance dynamic range and second video data having a second luminance dynamic range wider than the first luminance dynamic range; and transmitting the transmission signal generated. In the generating of the transmission signal, a signal level corresponding to a luminance value is limited to a value lower than a limit value that is predetermined, in a transition period provided for switching from one of the first video data and the second video data to the other.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. continuation application of PCT InternationalPatent Application Number PCT/JP2016/004021 filed on Sep. 2, 2016,claiming the benefit of priority of U.S. Provisional Patent ApplicationNo. 62/238,155 filed on Oct. 7, 2015 and Japanese Patent ApplicationNumber 2016-101958 filed on May 20, 2016, the entire contents of whichare hereby incorporated by reference.

BACKGROUND 1. Technical Field

The present disclosure relates to a video transmission method, a videoreception method, a video transmission apparatus, and a video receptionapparatus.

2. Description of the Related Art

The high dynamic range (HDR) has been drawing attention as a schemecovering a luminance range with an increased maximum luminance value inorder to represent bright light such as mirror-reflected light thatcannot be represented using current TV signals, with brightness closerto the actual brightness while maintaining dark part gradation ofexisting video. Specifically, the scheme covering the luminance rangesupported by the existing TV signals is called the standard dynamicrange (SDR) and has the maximum luminance value of 100 nits. Incontrast, the HDR is expected to have an increased maximum luminancevalue of at least 1000 nits (see ARIB STANDARD ARIB STD-B67 Version 1.0Jul. 3, 2015 (Non-Patent Literature (NPL) 1)).

SUMMARY

As for transmission or reception of video signals supporting a pluralityof luminance dynamic ranges as described above, there is a demand foreasier switching of the luminance dynamic range by a video receptionapparatus.

In view of the above, the present disclosure provides a videotransmission method, a video reception method, a video transmissionapparatus, or a video reception apparatus that enables easier switchingof a luminance dynamic range by a video reception apparatus.

A video transmission method according to an aspect of the presentdisclosure includes: generating a transmission signal including, in atime series, first video data having a first luminance dynamic range andsecond video data having a second luminance dynamic range wider than thefirst luminance dynamic range; and transmitting the transmission signalgenerated. In the generating of the transmission signal, a signal levelcorresponding to a luminance value is limited to a value lower than alimit value that is predetermined, in a transition period provided forswitching from one of the first video data and the second video data tothe other.

A video reception method according to an aspect of the presentdisclosure is a video reception method performed by a video receptionapparatus including a display. The video reception method includesreceiving a reception signal including, in a time series, first videodata having a first luminance dynamic range and second video data havinga second luminance dynamic range wider than the first luminance dynamicrange. In the reception signal, a signal level corresponding to aluminance value is limited to a value lower than a limit value that ispredetermined, in a transition period provided for switching from one ofthe first video data and the second video data to the other. Thereception signal includes first information for notifying, in a firstperiod immediately after a start of the transition period, switching ofa luminance dynamic range. The video reception method further includesswitching the luminance dynamic range of the display during a switchingallowed time that starts when the first information is obtained, theswitching allowed time being a length of time allowed for switching theluminance dynamic range.

Note that these general or specific aspects may be implemented by asystem, a method, an integrated circuit, a computer program, or acomputer-readable recording medium such as a compact disc read onlymemory (CD-ROM), or by any combination of a system, a method, anintegrated circuit, a computer program, and a recording medium.

The present disclosure can provide a video transmission method, a videoreception method, a video transmission apparatus, or a video receptionapparatus that enables easier switching of a luminance dynamic range bya video reception apparatus.

BRIEF DESCRIPTION OF DRAWINGS

These and other objects, advantages and features of the disclosure willbecome apparent from the following description thereof taken inconjunction with the accompanying drawings that illustrate a specificembodiment of the present disclosure.

FIG. 1 is a block diagram of a video reception apparatus according toEmbodiment 1;

FIG. 2 is a flow chart of processing performed by a display controlleraccording to Embodiment 1;

FIG. 3 is a flow chart of video reception processing according toEmbodiment 1;

FIG. 4 illustrates an operation performed when there is a change intransfer characteristics according to Embodiment 1;

FIG. 5 illustrates an operation performed when there is a change intransfer characteristics according to Embodiment 1;

FIG. 6 is a block diagram of a video transmission apparatus according toEmbodiment 1;

FIG. 7 illustrates a flow chart of video transmission processingaccording to Embodiment 1;

FIG. 8 illustrates an abnormal operation performed when there is achange in transfer characteristics according to Embodiment 2;

FIG. 9 is a block diagram of a video reception apparatus according toEmbodiment 2;

FIG. 10 is a flow chart of processing performed by a display controlleraccording to Embodiment 2;

FIG. 11 illustrates an example of a timestamp descriptor according toEmbodiment 3;

FIG. 12 illustrates an example of an extended timestamp descriptoraccording to Embodiment 3;

FIG. 13 illustrates an example of a video component descriptor accordingto Embodiment 3;

FIG. 14 illustrates a flow chart of processing performed by a displaycontroller according to Embodiment 3;

FIG. 15 illustrates a flow chart of video reception processing accordingto Embodiment 3;

FIG. 16 illustrates an example of a curve showing a relationship betweenthe electric signal level and the luminance of the HDR and a curveshowing a relationship between the electric signal level and theluminance of the SDR according to Embodiment 4;

FIG. 17 illustrates an operation performed for switching from the SDR tothe HDR according to Embodiment 4;

FIG. 18 illustrates an operation performed for switching from the HDR tothe SDR according to Embodiment 4;

FIG. 19 is a block diagram of a video transmission apparatus accordingto Embodiment 4;

FIG. 20 illustrates a flow chart of video transmission processingaccording to Embodiment 4;

FIG. 21 is a block diagram of a video reception apparatus according toEmbodiment 4; and

FIG. 22 illustrates a flow chart of video reception processing accordingto Embodiment 4.

DETAILED DESCRIPTION OF THE EMBODIMENTS (Underlying Knowledge FormingBasis of the Present Disclosure)

According to, for example, a video coding standard known as ITU-TH.265|ISO/IEC 23008-2 HEVC, the optical-electro transfer function (OETF)or electro-optical transfer function (EOTF) of a video signal isnotified of using a syntax known as transfer characteristics in videousability information (VUI) included in a sequence parameter set (SPS).Use of the transfer characteristics in the SPS enables notification ofswitching of transfer characteristics (transfer function) at frameaccuracy. A video reception apparatus determines a method of controllinga video display, based on the transfer characteristics.

According to the MPEG-2 transport stream (TS) standard, which is usedfor transmitting a video signal and an audio signal in a multiplexedmanner as in the case of TV broadcast etc., there is a known method ofincluding, in a descriptor of program-specific information (PSI), aparameter included in the aforementioned SPS and information related tothe parameter, and transmitting information related to an operation ofthe video reception apparatus in an upper layer. By using the descriptorof the PSI for the transfer characteristics as well, the video receptionapparatus can more easily determine a method of controlling the videodisplay. Since the PSI is generally inserted into a multiplexed streamat a constant cycle, the PSI is not synchronized with frames of a videosignal. Note that according to the MPEG-H MPEG media transport (MMT)standard, a structure similar to the PSI is defined as MMT-SI.

The transfer characteristics are defined by, for example, ITU-R BT.2020(hereinafter, BT.2020), ARIB STD-B67 (hereinafter, STD-B67), and SMPTEST2084 (hereinafter, ST2084). STD-B67 and ST2084 can handle a videosignal having a luminance ten to a hundred times as high as theconventional BT.2020, known as the high dynamic range (HDR). In contrastto the HDR, the dynamic range of the conventional BT.2020 etc., iscalled the standard dynamic range (SDR).

The TV broadcast compatible with the HDR may include both HDR programsand commercials and SDR programs and commercials. Accordingly, the videoreception apparatus needs to operate while switching the control on thedisplay, depending on whether the program/commercial is the HDR or theSDR.

A video transmission method according to an aspect of the presentdisclosure includes: generating a transmission signal including, in atime series, first video data having a first luminance dynamic range andsecond video data having a second luminance dynamic range wider than thefirst luminance dynamic range; and transmitting the transmission signalgenerated. In the generating of the transmission signal, a signal levelcorresponding to a luminance value is limited to a value lower than alimit value that is predetermined, in a transition period provided forswitching from one of the first video data and the second video data tothe other.

With this, the signal level of the video data is limited to a valuelower than the limit value in the transition period provided forswitching to video data having a different luminance dynamic range.Thus, the video reception apparatus need not change the luminancedynamic range of the display on a per-frame basis, for example, and itis only necessary to change the luminance dynamic range of the displayin the transition period. This as a result enables easier switching ofthe luminance dynamic range by the video reception apparatus.

For example, in the generating of the transmission signal, the signallevel corresponding to the luminance value may be limited to the valuelower than the limit value in a first transition period provided forswitching from the first video data to the second video data.

For example, in the generating of the transmission signal, the signallevel corresponding to the luminance value need not be limited to thevalue lower than the limit value in a second transition period providedfor switching from the second video data to the first video data.

For example, the transmission signal may include first information fornotifying, in a first period immediately after a start of the transitionperiod, switching of a luminance dynamic range.

For example, the first period may be a period of time from immediatelyafter the start of the transition period to a time preceding a switchingtime by a switching allowed time, the switching time being a time atwhich the one of the first video data and the second video data isswitched to the other, the switching allowed time being a length of timeallowed for the switching of the luminance dynamic range by a videoreception apparatus that receives the transmission signal.

For example, in the generating of the transmission signal, a videosignal may be generated by coding the first video data and the secondvideo data, and the transmission signal including the first informationmay be generated by multiplexing the video signal generated and an audiosignal.

For example, the transmission signal may include second informationindicating the transition period.

A video reception method according to an aspect of the presentdisclosure is a video reception method performed by a video receptionapparatus including a display. The video reception method includes:receiving a reception signal including, in a time series, first videodata having a first luminance dynamic range and second video data havinga second luminance dynamic range wider than the first luminance dynamicrange. In the reception signal, a signal level corresponding to aluminance value is limited to a value lower than a limit value that ispredetermined, in a transition period provided for switching from one ofthe first video data and the second video data to the other. Thereception signal includes first information for notifying, in a firstperiod immediately after a start of the transition period, switching ofa luminance dynamic range. The video reception method further includes:switching the luminance dynamic range of the display during a switchingallowed time that starts when the first information is obtained, theswitching allowed time being a length of time allowed for switching theluminance dynamic range.

With this, the signal level of the video data is limited to a valuelower than the limit value in the transition period provided forswitching to video data having a different luminance dynamic range.Thus, the video reception apparatus need not change the luminancedynamic range of the display on a per-frame basis, for example, and itis only necessary to change the luminance dynamic range of the displayin the transition period. This as a result enables easier switching ofthe luminance dynamic range by the video reception apparatus.

For example, the first period may be a period of time from immediatelyafter the start of the transition period to a time preceding a switchingtime by the switching allowed time, the switching time being a time atwhich the one of the first video data and the second video data isswitched to the other.

For example, the video reception method may further include: obtaining avideo signal and the first information by demultiplexing the receptionsignal multiplexed from the video signal and an audio signal; andobtaining the first video data and the second video data by decoding thevideo signal obtained.

For example, the reception signal may include second informationindicating the transition period.

A video transmission apparatus according to an aspect of the presentdisclosure includes: a generator that generates a transmission signalincluding, in a time series, first video data having a first luminancedynamic range and second video data having a second luminance dynamicrange wider than the first luminance dynamic range; and a transmitterthat transmits the transmission signal generated. The generator limits asignal level corresponding to a luminance value to a value lower than alimit value that is predetermined, in a transition period provided forswitching from one of the first video data and the second video data tothe other.

With this, the signal level of the video data is limited to a valuelower than the limit value in the transition period provided forswitching to video data having a different luminance dynamic range.Thus, the video reception apparatus need not change the luminancedynamic range of the display on a per-frame basis, for example, and itis only necessary to change the luminance dynamic range of the displayin the transition period. This as a result enables easier switching ofthe luminance dynamic range by the video reception apparatus.

A video reception apparatus according to an aspect of the presentdisclosure is a video reception apparatus including a display. The videoreception apparatus includes a receiver that receives a reception signalincluding, in a time series, first video data having a first luminancedynamic range and second video data having a second luminance dynamicrange wider than the first luminance dynamic range. In the receptionsignal, a signal level corresponding to a luminance value is limited toa value lower than a limit value that is predetermined, in a transitionperiod provided for switching from one of the first video data and thesecond video data to the other. The reception signal includes firstinformation for notifying, in a first period immediately after a startof the transition period, switching of a luminance dynamic range. Thevideo reception apparatus further includes: a display controller thatswitches the luminance dynamic range of the display during a switchingallowed time that starts when the first information is obtained, theswitching allowed time being a length of time allowed for switching theluminance dynamic range.

With this, the signal level of the video data is limited to a valuelower than the limit value in the transition period provided forswitching to video data having a different luminance dynamic range.Thus, the video reception apparatus need not change the luminancedynamic range of the display on a per-frame basis, for example, and itis only necessary to change the luminance dynamic range of the displayin the transition period. This as a result enables easier switching ofthe luminance dynamic range by the video reception apparatus.

Hereinafter, embodiments will be specifically described with referenceto the drawings.

Note that each of the embodiments described below illustrates a specificexample of the present disclosure. The numerical values, shapes,materials, structural elements, the arrangement and connection of thestructural elements, steps, the processing order of the steps, etc.,illustrated in the embodiments below are mere examples, and aretherefore not intended to limit the present disclosure. Furthermore,among the structural elements in the following embodiments, structuralelements not recited in any one of the independent claims representingthe most generic concepts are described as arbitrary structuralelements.

Embodiment 1

A video reception apparatus according to the present embodiment controlsa luminance dynamic range of a display at frame accuracy, using transfercharacteristics information indicating transfer characteristics at frameaccuracy. By doing so, the video reception apparatus can display moreappropriate video.

First, a configuration of the video reception apparatus according to thepresent embodiment will be described. FIG. 1 is a block diagram of videoreception apparatus 100 according to the present embodiment. Videoreception apparatus 100 is a TV, for example, and receives receptionsignal 111 transmitted via broadcast waves and displays video based onreception signal 111 received. Video reception apparatus 100 includesreceiver 101, demultiplexer 102, video decoder 103, display controller104, and display 105.

Receiver 101 receives reception signal 111. Reception signal 111 is asystem stream multiplexed from a video signal and an audio signal.

Demultiplexer 102 generates video signal 112 that is a video stream, bydemultiplexing (system decoding) reception signal 111. Furthermore,demultiplexer 102 outputs, as first transfer characteristics information113, transfer characteristics obtained from, for example, a descriptorincluded in reception signal 111. That is to say, first transfercharacteristics information 113 is included in a multiplexing layer.

Video decoder 103 generates video data 114 by decoding video signal 112.Furthermore, video decoder 103 outputs, as second transfercharacteristics information 115, transfer characteristics obtained fromthe SPS. That is to say, second transfer characteristics information 115is included in a video coding layer.

Second transfer characteristics information 115 is information forspecifying a transfer function (OETF or EOTF) at frame accuracysupporting a luminance dynamic range of video data 114. For example,second transfer characteristics information 115 is information forspecifying, at frame accuracy, a first transfer function correspondingto a first luminance dynamic range (SDR) or a second transfer functioncorresponding to a second luminance dynamic range (HDR) wider than thefirst luminance dynamic range. That is to say, second transfercharacteristics information 115 indicates whether video data 114 is SDRvideo data or HDR video data. Moreover, when there is more than onemethod for the HDR, second transfer characteristics information 115 mayindicate the method of the HDR. That is to say, second transfercharacteristics information 115 indicates the luminance dynamic range ofvideo data 114. For example, second transfer characteristics information115 indicates one of a plurality of predetermined luminance dynamicranges.

The SPS is control information included in video signal 112. Here, thecontrol information is provided on a sequence-by-sequence basis (on aplurality of frames-by-a plurality of frames basis).

Display controller 104 generates control information 116 for controllingdisplay 105, according to first transfer characteristics information 113and second transfer characteristics information 115.

Display 105 displays video data 114 while controlling the luminancedynamic range at frame accuracy according to control information 116(that is, first transfer characteristics information 113 and secondtransfer characteristics information 115). Display 105 includes videocharacteristics converter 106 and display device 107.

Video characteristics converter 106 generates input signal 117 byconverting video data 114 according to control information 116.Specifically, video characteristics converter 106 converts video data114 into input signal 117 using a transfer function indicated in firsttransfer characteristics information 113 or second transfercharacteristics information 115.

Display device 107 is, for example, a liquid crystal panel, and changesthe luminance dynamic range of video displayed, according to controlinformation 116. For example, when display device 107 is a liquidcrystal panel, display device 107 changes the maximum luminance of abacklight.

Next, an operation of video reception apparatus 100 will be described.Note that although FIG. 1 illustrates a configuration in which bothfirst transfer characteristics information 113 and second transfercharacteristics information 115 are used, it is only necessary that atleast second transfer characteristics information 115 is used.Hereinafter, control performed using second transfer characteristicsinformation 115 will be described in detail.

FIG. 2 is a flow chart of display control processing performed bydisplay controller 104. Note that the processing illustrated in FIG. 2is performed on a frame-by-frame basis or every time second transfercharacteristics information 115 is changed.

First, display controller 104 determines which one of the SDR and theHDR is indicated by second transfer characteristics information 115(S101).

When the HDR is indicated by second transfer characteristics information115 (YES in S101), display controller 104 outputs control information116 for HDR display (S102). With this, display 105 displays video in aluminance dynamic range corresponding to the HDR.

On the other hand, when the SDR is indicated by second transfercharacteristics information 115 (NO in S101), display controller 104outputs control information 116 for SDR display (S103). With this,display 105 displays video in a luminance dynamic range corresponding tothe SDR.

In such a manner, by switching control information 116 according tosecond transfer characteristics information 115 notified of at frameaccuracy, it is possible to synchronize the switching of the transfercharacteristics and the control on display 105.

Note that when there are a plurality of HDR methods (for example,STD-B67 and ST2084), control information 116 for HDR display may includeidentification information identifying an HDR method. This allowsdisplay 105 to display video in a luminance dynamic range of thecorresponding method.

FIG. 3 is a flow chart of video reception processing performed by videoreception apparatus 100. First, receiver 101 receives reception signal111 (S111). Next, demultiplexer 102 generates video signal 112 bydemultiplexing reception signal 111 (S112). Next, video decoder 103generates video data 114 and obtains second transfer characteristicsinformation 115 by decoding video signal 112 (S113).

Next, display controller 104 controls the luminance dynamic range ofdisplay 105 according to second transfer characteristics information115. Specifically, display controller 104 determines, for each frame, atframe accuracy, whether the frame is an HDR frame or an SDR frame, basedon second transfer characteristics information 115 (S114). When theframe is an HDR frame (YES in S114), display 105 displays video in theluminance dynamic range of the HDR (S115). When the frame is an SDRframe (NO in S114), display 105 displays video in the luminance dynamicrange of the SDR (S116).

FIG. 4 illustrates switching from an SDR program to an HDR program. FIG.5 illustrates switching from an HDR program to an SDR program. Asillustrated in FIG. 4 and FIG. 5, the above processing enablesappropriate switching between the SDR and the HDR at frame accuracy.

Hereinafter, video transmission apparatus 200 that generatestransmission signal 212 corresponding to aforementioned reception signal111 will be described. FIG. 6 is a block diagram of video transmissionapparatus 200 according to the present embodiment. Video transmissionapparatus 200 illustrated in FIG. 6 includes generator 201 andtransmitter 202.

Generator 201 generates transmission signal 212 including video data andsecond transfer characteristics information that is information forspecifying, at frame accuracy, a transfer function corresponding to theluminance dynamic range of the video data. Generator 201 includes videocoder 203 and multiplexer 204.

FIG. 7 is a flow chart of video transmission processing performed byvideo transmission apparatus 200. First, video coder 203 generates videosignal 211 by coding video data and second transfer characteristicsinformation (S201). The second transfer characteristics informationcorresponds to second transfer characteristics information 115 describedabove, and is information for specifying, at frame accuracy, the firsttransfer function corresponding to the first luminance dynamic range(for example, the SDR) or the second transfer function corresponding tothe second luminance dynamic range (for example, the HDR) wider than thefirst luminance dynamic range. The second transfer characteristicsinformation is stored in the SPS included in video signal 211.

Next, multiplexer 204 generates transmission signal 212 by multiplexingcoded video signal 211 and an audio signal (S202). Next, transmitter 202transmits transmission signal 212 generated (S203).

With the above processing, video transmission apparatus 200 generatestransmission signal 212 including the second transfer characteristicsinformation for specifying a transfer function at frame accuracy. Withthis, the video reception apparatus that receives transmission signal212 can control the luminance dynamic range of the display at frameaccuracy, and thus can display more appropriate video.

Embodiment 2

With the TV broadcast, an error may occur due to the radio wavecondition of terrestrial waves, a satellite, etc. FIG. 8 illustrates thecase of a reception error caused by radio disturbance, for example. FIG.8 illustrates the case where, when switching from the SDR to the HDR,radio disturbance or the like occurs after the video reception apparatusobtains second transfer characteristics information 115 included in theSPS, and, as a result, a loss of a video stream occurs, causinginability to obtain the initial frame of the HDR program. In this case,video decoder 103 continues to display an immediately preceding framefor error concealment. In other words, the frame of the SDR program isrepeatedly displayed.

In this case, a subsequent frame refers to this frame, and thus abnormalvideo mixed with video of a past program is displayed as subsequentvideo.

Moreover, immediately after the switching from the SDR to the HDR, theluminance dynamic range of the display is set to the HDR, causing theframe of the SDR program to be displayed in the luminance dynamic rangeof the HDR. This results in a problem of displaying video having aluminance higher than intended.

The present embodiment describes a video reception apparatus thataddresses this problem. FIG. 9 is a block diagram of video receptionapparatus 100A according to the present embodiment. Video receptionapparatus 100A illustrated in FIG. 9 includes, in addition to theelements included in video reception apparatus 100 illustrated in FIG.1, abnormality detector 108 and message superimposer 109 included indisplay 105A. Moreover, display controller 104A has an additionalfunction.

Abnormality detector 108 determines whether video data 114 (video signal112) is correctly obtained. Specifically, abnormality detector 108detects a packet loss based on the sequence number of each packet, andobtains the starting position of frame data by analyzing the payload ofeach packet, so as to determine whether all the frame data is obtained(normal) or only a part of the frame data is obtained (abnormal).Furthermore, abnormality detector 108 outputs abnormality notifyinginformation 118 indicating the determination result to displaycontroller 104A. That is to say, display controller 104A is notifiedthat an abnormal condition has occurred, or is notified of informationfor specifying an abnormal frame.

Display controller 104A generates control information 116 and message119 according to abnormality notifying information 118 in addition tofirst transfer characteristics information 113 and second transfercharacteristics information 115. Specifically, when there is anabnormality, display controller 104A generates message 119 indicatingthat there is an abnormality, and generates control information 116 forSDR display.

Message superimposes 109 generates input signal 120 by superimposingmessage 119 on video data (input signal 117) according to controlinformation 116 and message 119, and outputs generated input signal 120to display device 107. With this, a message such as “Error has occurred”is displayed on display device 107, notifying the viewer that it is nota failure of the apparatus.

FIG. 10 is a flow chart of display control processing performed bydisplay controller 104A. First, display controller 104A determineswhether second transfer characteristics information 115 is updated(S121). When second transfer characteristics information 115 is updated(YES in S121), display controller 104A starts determination regardingthe switching of the display control.

First, display controller 104A determines whether video data iscorrectly obtained. Specifically, display controller 104A determineswhether an intra coded frame is normally decoded, based on abnormalitynotifying information 118 (S122). When the intra coded frame is notnormally decoded (NO in S122), display controller 104A outputs controlinformation 116 for SDR display (S123). With this, display 105 displaysvideo in a luminance dynamic range corresponding to the SDR. That is tosay, when determining that the video data is not correctly obtained,display controller 104A sets the SDR (the first luminance dynamic range)as the luminance dynamic range of display 105.

If an error occurs when switching from one luminance dynamic range toanother, a frame displayed may include pixels of a frame displayedbefore the switch. In contrast, according to the present embodiment, insuch a case, setting the display control for SDR display as the displaycontrol makes it possible to inhibit a frame of the SDR program frombeing displayed with the HDR high luminance settings.

When an intra coded frame that guarantees interrupt playback, such asIDR or CRA of HEVC, is normally decoded (YES in S122), the displaycontrol is switched in the same manner as in Embodiment 1. That is tosay, display controller 104A determines which one of the SDR and the HDRis indicated by updated second transfer characteristics information 115(S124). When the HDR is indicated by second transfer characteristicsinformation 115 (YES in S124), display controller 104A outputs controlinformation 116 for HDR display (S125). On the other hand, when the SDRis indicated by second transfer characteristics information 115 (NO inS124), display controller 104A outputs control information 116 for SDRdisplay (S126).

In such a manner, video reception apparatus 100A according to thepresent embodiment can inhibit excessively bright video from beingdisplayed when an error occurs, by displaying video in the luminancedynamic range of the SDR when the error occurs.

Embodiment 3

The present embodiment describes the details of first transfercharacteristics information 113 and processing performed using firsttransfer characteristics information 113. First, an example of transfercharacteristics obtained by demultiplexer 102 will be described.

When the MMT is used as the multiplexing scheme, the presentationtimestamp (PTS) and the decoding timestamp (DTS) of an access unit(equivalent to a picture) that comes first in the decoding order(hereinafter also referred to as a leading access unit) in a randomaccess unit called a media processing unit (MPU) can be transmittedusing a descriptor. For example, according to STD-B60 of the Associationof Radio Industries and Business (ARIB), either (i) the PTS of theleading access unit of the MPU is transferred or (ii) the DTS of theleading access unit of the MPU and the DTS and the PTS of a subsequentaccess unit are transferred, as control information for a program, usingan MPU timestamp descriptor or an MPU extended timestamp descriptor.

FIG. 11 illustrates an example of a syntax of an MPU timestampdescriptor (MPU_Timestamp_Discriptor) including HDR identificationinformation 301. FIG. 12 illustrates an example of a syntax of an MPUextended timestamp descriptor (MPU_Extended_Timestamp_Discriptor)including HDR identification information 301.

As illustrated in FIG. 11 or FIG. 12, by extending the MPU timestampdescriptor or the MPU extended timestamp descriptor, it is possible toadd, to transmission signal 212 (reception signal 111), HDRidentification information 301 (mpu_hdr_indicator) indicating whetherthe EOTF of the access unit included in the MPU corresponds to the HDRor the SDR. Note that when there are two or more EOTFs corresponding tothe HDR, e.g., when STD-B67 and SMPTE ST2084 are both available, HDRidentification information 301 may include information for identifyingthe type of the EOTF corresponding to the HDR. Furthermore, a differentdescriptor may be used as long as the EOTF identification informationprovided per MPU can be transmitted.

When MPEG-2 TS is used as the multiplexing scheme, the PTS or the DTS ofthe access unit may be associated with the EOTF identificationinformation by extending 13818-1 AMD6 (delivery of timeline for externaldata). Alternatively, the EOTF identification information provided perrandom access unit may be stored using a descriptor in the same manneras the MMT, or, the EOTF identification information provided per randomaccess unit may be signaled using header information of the PES or theTS.

In such a manner, first transfer characteristics information 113 isincluded in the control information that is included in transmissionsignal 212 (reception signal 111). Here, the control information isprovided per random access unit. Note that the random access unit is aunit including a plurality of access units (a plurality of frames) inwhich random access is guaranteed.

First transfer characteristics information 113 may be stored ininformation provided per program including a plurality of MPUs, insteadof being stored as information provided per MPU such as the MPUtimestamp descriptor. According to the ARIB, the resolution, aspectratio, frame rate, etc., of a video stream are stored in a videocomponent descriptor that is information provided per program. Thus,first transfer characteristics information 113 can also be stored in thevideo component descriptor. However, since information provided perprogram is periodically transmitted, e.g., every 0.5 seconds or every0.1 seconds, the information cannot be updated per frame or per randomaccess unit in some cases. Therefore, in such cases, transfercharacteristics information that will be valid in the future is stored,as well as currently-valid transfer characteristics information.

FIG. 13 illustrates an example of a syntax of a video componentdescriptor. Current_EOTF (first information) indicates a currently-validEOTF (transfer function), and EOTF_update_flag (second information)indicates whether the EOTF will be switched in the future. That is tosay, EOTF_update_flag (second information) indicates whether or not thetransfer function will be switched in the program.

When EOTF_update_flag (second information) indicates that the EOTF willbe switched, the video component descriptor includes new_EOTF (thirdinformation) indicating a new EOTF to be switched to, andnew_EOTF_start_mpu_sequence_number (fourth information) indicating thesequence number of the MPU in which the new EOTF will be valid. That isto say, new_EOTF_start_mpu_sequence_number (fourth information) isinformation for specifying a random access unit in which the EOTF willbe switched.

Note that when there is one type of HDR, it is only necessary toindicate whether the EOTF corresponds to the HDR or the SDR. That is tosay, the field of new_EOTF may be omitted because the new EOTF can bedetermined from EOTF_update_flag only.

By transmitting the transfer characteristics in the above-describedmanner, the video reception apparatus can obtain the transfercharacteristics of the access unit included in the MPU, based only onthe information about the multiplexing layer (attribute information ofmultiplexed AV data, and header information of a packet in which the AVdata is stored). Furthermore, with the seamless connection according tothe conventional ARIB, the PID of a TS packet storing a video stream oran asset ID (or a packet ID) of an MMT packet is switched when an itemsuch as the resolution is switched. Such switching has disadvantages,e.g., it is difficult to manage a system target decoder (STD) buffer inpackets having the same ID, or data supply from the transmission sidetemporarily stops at the switching point. These problems can be solvedby adopting the present technique.

Note that the present technique is also applicable to the case ofseamlessly switching a plurality of audio codecs.

The configuration of video reception apparatus 100A according to thepresent embodiment is different from that of Embodiment 2 in that afunction is added to display controller 104A in the configurationillustrated in FIG. 9.

First, prior to decoding video signal 112, demultiplexer 102 obtains theabove-described transfer characteristics (such as HDR identificationinformation 301) from the information about the multiplexing layer, andoutputs, to display controller 104A, first transfer characteristicsinformation 113 for specifying the transfer characteristics obtained.

Since video reception apparatus 100A can obtain first transfercharacteristics information 113 prior to decoding video signal 112,first transfer characteristics information 113 can be obtained beforesecond transfer characteristics information 115 timewise. Accordingly,it is possible to extend the time between obtainment of the transfercharacteristics information by display controller 104A and the actualcontrol on video characteristics converter 106 and display device 107 bydisplay controller 104A. Especially when the transfer characteristicsare switched per access unit, an increase in the frame rate places agreater restriction on time if the transfer characteristics are obtainedbased on the decoding result. Therefore, it is highly beneficial toobtain the transfer characteristics from the multiplexing layer inadvance.

FIG. 14 is a flow chart of display control processing performed bydisplay controller 104A. The processing illustrated in FIG. 14 isdifferent from the processing illustrated in FIG. 10 in terms of StepsS121A and S124A.

In Step S121A, display controller 104A determines whether first transfercharacteristics information 113 is updated in addition to secondtransfer characteristics information 115. Furthermore, since the leadingaccess unit of the MPU is an intra coded frame, in Step S122, displaycontroller 104A, when operating based on first transfer characteristicsinformation 113, operates based on (i) first transfer characteristicsinformation 113 corresponding to the sequence number(mpu_sequence_number) of the same MPU and (ii) the result of decodingthe intra coded frame. In Step S124A, display controller 104A operatesbased on first transfer characteristics information 113 or secondtransfer characteristics information 115.

Note that although FIG. 14 illustrates the example where first transfercharacteristics information 113 and second transfer characteristicsinformation 115 are both used, first transfer characteristicsinformation 113 only may be used instead.

FIG. 15 is a flow chart of video reception processing performed by videoreception apparatus 100A according to the present embodiment. First,receiver 101 receives reception signal 111 (S111). Next, demultiplexer102 generates video signal 112 and obtains first transfercharacteristics information 113 by demultiplexing reception signal 111(5112A).

Here, first transfer characteristics information 113 is information forspecifying, per random access unit (per MPU), a transfer function (OETFor EOTF) corresponding to the luminance dynamic range of video data 114(video signal 112). For example, first transfer characteristicsinformation 113 is information for specifying, per random access unit,the first transfer function corresponding to the first luminance dynamicrange (SDR) or the second transfer function corresponding to the secondluminance dynamic range (HDR) wider than the first luminance dynamicrange. That is to say, first transfer characteristics information 113indicates whether video data 114 is SDR video data or HDR video data.Moreover, when there is more than one method for the HDR, first transfercharacteristics information 113 may indicate the method of the HDR. Thatis to say, first transfer characteristics information 113 indicates theluminance dynamic range of video data 114. For example, first transfercharacteristics information 113 indicates one of a plurality ofpredetermined luminance dynamic ranges.

Next, video decoder 103 generates video data 114 by decoding videosignal 112 (S113).

Next, display controller 104A controls the luminance dynamic range ofdisplay 105 according to first transfer characteristics information 113.Specifically, display controller 104A determines, per MPU, whether datain the MPU corresponds to the HDR or the SDR, based on first transfercharacteristics information 113 (S114A). When the data in the MPUcorresponds to the HDR (YES in S114A), display 105 displays video in theluminance dynamic range of the HDR (S115). When the data in the MPUcorresponds to the SDR (NO in S114A), display 105 displays video in theluminance dynamic range of the SDR (S116).

With the above processing, video reception apparatus 100A can controlthe luminance dynamic range of display 105 per random access unit, andthus can display more appropriate video. Further, since video receptionapparatus 100A can obtain the transfer characteristics prior to decodingvideo signal 112 by using first transfer characteristics information 113included in the multiplexing layer, it is possible to easily switch thetransfer characteristics.

The configuration and operation of video transmission apparatus 200 thatgenerates transmission signal 212 corresponding to reception signal 111described above are generally the same as those in Embodiment 1described above.

Specifically, in Step S202 illustrated in FIG. 7, multiplexer 204generates transmission signal 212 including first transfercharacteristics information 113.

In such a manner, video transmission apparatus 200 generatestransmission signal 212 including the first transfer characteristicsinformation for specifying the transfer function per random access unit.With this, the video reception apparatus that receives transmissionsignal 212 can control the luminance dynamic range of the display perrandom access unit, and thus can display more appropriate video.Moreover, since first transfer characteristics information 113 isincluded in the multiplexing layer, the video reception apparatus caneasily switch the transfer characteristics.

Hereinafter, a variation of the present embodiment will be described.

In the case where a video reception apparatus such as a set top box(STB), a DVD device, or a Blu-ray (registered trademark) device receivesa system stream and outputs a stream to a display device such as a TV,the video reception apparatus and the display device are connected via acommunication protocol such as HDMI (registered trademark). Here, withHDMI (registered trademark) etc., protocol re-authentication occurs whenthe resolution or the like of the stream is switched.

Accordingly, if there is a possibility that the resolution will beswitched, e.g., between 2K (e.g., 1920 pixels×1080 pixels) and 4K (e.g.,3840 pixels×2160 pixels), the video reception apparatus desirablyoutputs a video signal compliant with the maximum resolution whenstarting the reproduction. That is to say, if there is a mixture of 2Kstreams and 4K streams, the reception apparatus upconverts the 2Kstreams into 4K streams and outputs the 4K streams, even when thereproduction starts with the 2K streams. By doing so, even when a signalis switched to a 4K signal halfway through, the resolution maintains at4K and switching of the resolution does not occur. For example, when theswitching occurs between the SDR at 2K and the HDR at 4K, the videoreception apparatus converts a 2K stream for the SDR into a 4K streamfor the SDR, and outputs the 4K stream for the SDR.

That is to say, the video signal (video data 114) has a resolution thatis a first resolution or a second resolution higher than the firstresolution. When the resolution of the video signal switches between thefirst resolution and the second resolution, video reception apparatus100A converts the video signal having the first resolution into thevideo signal having the second resolution.

In the broadcasting, identification information identifying the maximumresolution allowable in the broadcasting service is indicated by, forexample, a descriptor, and thus, the video reception apparatus mayoperate in such a manner that the signal output to HDMI (registeredtrademark) has the maximum resolution constantly. For example, in thecase of the ultra high definition (UHD) service, the maximum resolutionis defined as 4K or 8K. When the multiplexing scheme is the TS, themaximum resolution is defined as 2K, whereas when the multiplexingscheme is the MMT, the maximum resolution is defined as 4K. Accordingly,the video reception apparatus may constantly convert the video signalinto a video signal having the maximum resolution supporting themultiplexing scheme, and output the video signal having the maximumresolution.

That is to say, when the resolution of the video signal (video data 114)is lower than the maximum resolution defined by the broadcasting servicefor reception signal 111, video reception apparatus 100A converts theresolution of the video signal into the maximum resolution.

Embodiment 4

In the present embodiment, the signal level of the video signal islimited when the luminance dynamic range is switched between the SDR andthe HDR. This enables easier switching of the luminance dynamic range bythe video reception apparatus.

First, interchangeable characteristics of STD-B67 corresponding to theHDR will be described. In terms of device design, it is important toallow a certain length of delay from when the transfer characteristicsare obtained to when video characteristics converter 106 and displaydevice 107 are controlled. As an example where such a delay is allowed,it has been described earlier that the switching of the transfercharacteristics is notified in advance using a descriptor in amultiplexing layer.

However, even when the switching of the transfer characteristics isnotified in advance, it is necessary to control video characteristicsconverter 106 and display device 107 in synchronization with a framethat switches from the SDR to the HDR or from the HDR to the SDR.

Meanwhile, when the luminance value of the SDR (BT.2020, for example) atthe electric signal level of 1.0 is adjusted to a level on the order of400% to 500% with respect to 1200% for STD-B67 (HDR), the shape of acurve showing a relationship between the electric signal level and theluminance of STD-B67 generally matches the shape of a curve for the SDRat low luminance.

FIG. 16 illustrates an example of a curve showing a relationship betweenthe electric signal level and the luminance of the HDR (STD-B67) and acurve showing a relationship between the electric signal level and theluminance of the SDR (BT.2020) according to Embodiment 4. As illustratedin FIG. 16, the HDR curve and the SDR curve generally match each otherin the low luminance range. Thus, if the luminance range of the HDRvideo data converted by STD-B67 is equivalent to the luminance range inwhich the shapes of the above-described curves generally match, even adisplay device that supports only the SDR can reproduce video that doesnot give the viewer a feeling of visual strangeness. That is to say,STD-B67 has the characteristics of interchangeability between the SDRand the HDR (interchangeable characteristics). Hereinafter, a range ofthe electric signal level corresponding to the luminance range in whichthe shape of the SDR curve and the shape of the HDR (STD-B67) curvegenerally match each other is referred to as an interchangeable region.In other words, as illustrated in FIG. 16, the interchangeable region isa predetermined range of the electric signal level, and is a range ofthe electric signal level lower than a predetermined limit value.

For example, in FIG. 16, electric signal level A is within theinterchangeable region, and thus STD-B67 and BT.2020 are equivalent inthe luminance value. On the other hand, the luminance valuecorresponding to electric signal level B is n1 for BT.2020 and n2 forSTD-B67, which are significantly different from each other. This resultsin a problem that at the time of switching from the HDR to the SDR,when, for example, there is a delay in the switching of the transfercharacteristics by the video reception apparatus and SDR pixels outsidethe interchangeable region are thus reproduced as HDR pixels in error,the pixels are reproduced at an improperly high luminance value.

Hereinafter, a method for providing a transition period in the switchingof the transfer characteristics according to the present embodiment willbe described. By making use of the above-described interchangeablecharacteristics, it is possible to display video that does not give theviewer a feeling of strangeness even when the video reception apparatusdoes not switch the transfer characteristics in synchronization with theframe.

First, with reference to FIG. 17, an operation performed for switchingfrom an SDR program to an HDR program will be described. A certain timeperiod at the end of the SDR program is set as a period of transitionfrom the SDR to the HDR (a transition period). In the transition period,video data is generated using the electric signal level within theinterchangeable region. By doing so, regardless of whether the controlsettings for the SDR display are used or the control settings for theHDR display are used in the transition period, video having a visuallyequivalent luminance is reproduced. It is thus possible to inhibitreproduction of video at an improperly high luminance in error.

The switching of the transfer characteristics can be notified using theinformation included in the multiplexing layer such as the videocomponent descriptor illustrated in FIG. 11 to FIG. 13. Here, given thatthe transition period is T second(s) and a length of time allowed forthe switching of the transfer characteristics by the video receptionapparatus (a switching allowed time) is S second(s), a descriptor thatnotifies the switching of the transfer characteristics is transmitted ina period of (T−S) second(s) from the start of the transition period. Byswitching the display control within S second(s) from obtainment of thedescriptor, the video reception apparatus can complete the switching ofthe display control before the HDR program starts.

In such a manner, by providing the transition period and restricting thehighest luminance of the image in the transition period, and notifyingthe switching of the transfer characteristics using the multiplexinglayer, the video reception apparatus can switch the display controlbased only on the information included in the multiplexing layer withouthaving to analyze the video stream (video signal 112).

Note that the transition period may be notified as information for thevideo stream such as an SEI message, even though analysis of the videostream is required.

Next, an operation performed for switching from an HDR program to an SDRprogram will be described. In this case, too, the transition period canbe provided in the same manner as in the operation performed forswitching from an SDR program to an HDR program described above.

Here, when HDR pixels outside the interchangeable luminance range arereproduced as SDR pixels, the pixels are reproduced at a luminance valuelower than the actual luminance value. Therefore, such reproduction inthis case is less likely to adversely affect the viewer in terms ofhealth etc. As such, as illustrated in FIG. 18, for the switching froman HDR program to an SDR program, the range of the electric signal levelneed not be limited to the interchangeable region in the transitionperiod.

Note that the above-described interchangeable region is a predeterminedrange of the electric signal level, and is a range of the electricsignal level lower than a predetermined limit value. For example, BBCResearch & Development White Paper WHP 283, July 2014 (NPL 2) describesthe characteristics of these SDR and HDR curves (p. 9, FIG. 3, forexample). That is to say, the lower limit value of the interchangeableregion is the electric signal level of 0, that is, black.

Hereinafter, a video transmission apparatus and a video receptionapparatus that implement the above function will be described. FIG. 19is a block diagram of video transmission apparatus 200B according to thepresent embodiment. Video transmission apparatus 200B includes generator201B and transmitter 202. Generator 201B generates transmission signal212B including, in a time series, first video data having a firstluminance dynamic range (SDR) and second video data having a secondluminance dynamic range (HDR) wider than the first luminance dynamicrange (SDR). Generator 201B includes video data generator 205, videocoder 203, and multiplexer 204. Transmitter 202 transmits transmissionsignal 212B.

FIG. 20 is a flow chart of video transmission processing performed byvideo transmission apparatus 200B. First, video data generator 205generates video data 213 (S204). At this time, video data generator 205,as described above, limits the signal level corresponding to theluminance value to a level within the interchangeable region in thetransition period provided for switching from one of the first videodata and the second video data to the other. That is to say, video datagenerator 205 limits the signal level to a value lower than apredetermined limit value. The transition period is a period immediatelybefore the switching time, for example.

Furthermore, as described above, the signal level is limited only whenthe luminance dynamic range is switched from the SDR and the HDR, andthe signal level need not be limited when the luminance dynamic range isswitched from the HDR to the SDR. That is to say, the signal levelcorresponding to the luminance value may be limited to a value lowerthan the limit value in a first transition period provided for switchingfrom the first video data (SDR) to the second video data (HDR), whereasthe signal level corresponding to the luminance value need not belimited to a value lower than the limit value in a second transitionperiod provided for switching from the second video data (HDR) to thefirst video data (SDR).

Next, video coder 203 generates video signal 211B by coding video data213 (S201). Next, multiplexer 204 generates transmission signal 212B bymultiplexing video signal 211B generated and an audio signal (S202).Then, transmitter 202 transmits transmission signal 212B (S203).

As illustrated in FIG. 17 and FIG. 18, transmission signal 212B includesfirst information (a switching notifying descriptor) for notifying theswitching of the luminance dynamic range in a first period immediatelyafter the start of the transition period. For example, the first periodis a period of time from immediately after the start of the transitionperiod to a time preceding a switching time by a switching allowed timethat is a length of time allowed for the switching of the luminancedynamic range by the video reception apparatus that receivestransmission signal 212B.

The first information (the switching notifying descriptor) istransmitted using the multiplexing layer. That is to say, multiplexer204 generates transmission signal 212B including the first information(the switching notifying descriptor) by multiplexing video signal 211Band an audio signal. Transmission signal 212B may include secondinformation indicating the transition period.

FIG. 21 is a block diagram of video reception apparatus 100B accordingto the present embodiment. Video reception apparatus 100B receivesreception signal 111B that is transmission signal 212B generated byvideo transmission apparatus 200B illustrated in FIG. 19. Note that thebasic configuration is the same as that of video reception apparatus 100illustrated in FIG. 1, but the function of display controller 104B isdifferent from that of display controller 104.

FIG. 22 is a flow chart of video reception processing performed by videoreception apparatus 100B. First, receiver 101 receives reception signal111B including, in a time series, first video data having a firstluminance dynamic range (SDR) and second video data having a secondluminance dynamic range (HDR) wider than the first luminance dynamicrange (SDR) (S111). Here, as described above, in reception signal 111B,the signal level corresponding to the luminance value is limited to avalue lower than a predetermined limit value in the transition periodprovided for switching from one of the first video data and the secondvideo data to the other.

Next, demultiplexer 102 obtains video signal 112 by demultiplexingreception signal 111B that is multiplexed from a video signal and anaudio signal (S112). The multiplexing layer includes switching notifyingdescriptor 121 (the first information), and demultiplexer 102 obtainsswitching notifying descriptor 121. Here, switching notifying descriptor121 is information for notifying the switching of the luminance dynamicrange in the first period immediately after the start of the transitionperiod.

When switching notifying descriptor 121 is received (YES in S114B),display controller 104B switches the luminance dynamic range of display105 during the switching allowed time that starts when switchingnotifying descriptor 121 is obtained (S115B). Here, the switchingallowed time is a length of time allowed for the switching of theluminance dynamic range.

Note that although not illustrated, video decoder 103 obtains video data114 by decoding video signal 112 in parallel with the processing inSteps S114B and S115B. Display 105 displays video data 114 in thecurrently-set luminance dynamic range.

As described above, in the present embodiment, the signal level of videodata is limited to a value lower than the limit value in the transitionperiod provided for switching to video data having a different luminancedynamic range. With this, the video reception apparatus need not changethe luminance dynamic range of the display on a per-frame basis, forexample, and it is only necessary to change the luminance dynamic rangeof the display in the transition period. Thus, the video receptionapparatus can easily control the switching of the luminance dynamicrange.

Hereinbefore, the video reception apparatus and the video transmissionapparatus according to embodiments of the present disclosure have beendescribed; however, the present disclosure is not limited to theseembodiments.

Moreover, each of processing members included in the video receptionapparatus and the video transmission apparatus according to the aboveembodiments are typically implemented as LSI which is an integratedcircuit. These may be implemented in a single chip individually, or in asingle chip that includes some or all of them.

Moreover, the method of circuit integration is not limited to LSI.Integration may be implemented with a specialized circuit or a generalpurpose processor. It is also acceptable to use: a field programmablegate array (FPGA) that is programmable after the LSI is manufactured;and a reconfigurable processor that allows reconfiguration of theconnections and settings of the inner circuit cells of the LSI circuit.

Further, in each embodiment described above, each structural element maybe implemented by dedicated hardware or by execution of a softwareprogram appropriate for the structural element. Each structural elementmay also be implemented by reading and execution, by a program executingunit such as a central processing unit (CPU) or a processor, of asoftware program recorded on a recording medium such as a hard disk orsemiconductor memory.

Furthermore, the present disclosure may be implemented as a videoreception method performed by a video reception apparatus or as a videotransmission method performed by a video transmission apparatus.

The division of the functional blocks in the block diagrams is a mereexample. A plurality of functional blocks may be implemented as onefunctional block, or one functional block may be divided into aplurality of blocks, or a part of the functions may be transferred toanother functional block. Moreover, the functions of a plurality offunctional blocks having similar functions may be performed by singlehardware or software in parallel or by time division.

Furthermore, since the processing order of the steps in each flow chartis one example given for specifically describing the present disclosure,other processing orders may be adopted. In addition, a part of the stepsmay be performed simultaneously (in parallel) with another step.

Hereinbefore, a video reception apparatus and a video transmissionapparatus according to one or more aspects have been described based onembodiments; however, the present disclosure is not limited to theseembodiments. Various modifications to these embodiments that areconceivable to those skilled in the art, as well as embodimentsresulting from combinations of structural elements of differentembodiments may be included within the scope of one or more aspects, aslong as such modifications and embodiments do not depart from theessence of the present disclosure.

Although only some exemplary embodiments of the present disclosure havebeen described in detail above, those skilled in the art will readilyappreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of the present disclosure. Accordingly, all suchmodifications are intended to be included within the scope of thepresent disclosure.

INDUSTRIAL APPLICABILITY

The present disclosure is applicable to a video reception apparatus suchas a TV, and a video transmission apparatus.

What is claimed is:
 1. A video transmission method, comprising:generating a transmission signal including, in a time series, firstvideo data having a first luminance dynamic range and second video datahaving a second luminance dynamic range wider than the first luminancedynamic range; and transmitting the transmission signal generated,wherein, in the generating of the transmission signal, a signal levelcorresponding to a luminance value is limited to a value lower than alimit value that is predetermined, in a transition period provided forswitching from one of the first video data and the second video data tothe other.
 2. The video transmission method according to claim 1,wherein in the generating of the transmission signal, the signal levelcorresponding to the luminance value is limited to the value lower thanthe limit value in a first transition period provided for switching fromthe first video data to the second video data.
 3. The video transmissionmethod according to claim 2, wherein in the generating of thetransmission signal, the signal level corresponding to the luminancevalue is not limited to the value lower than the limit value in a secondtransition period provided for switching from the second video data tothe first video data.
 4. The video transmission method according toclaim 1, wherein the transmission signal includes first information fornotifying, in a first period immediately after a start of the transitionperiod, switching of a luminance dynamic range.
 5. The videotransmission method according to claim 4, wherein the first period is aperiod of time from immediately after the start of the transition periodto a time preceding a switching time by a switching allowed time, theswitching time being a time at which the one of the first video data andthe second video data is switched to the other, the switching allowedtime being a length of time allowed for the switching of the luminancedynamic range by a video reception apparatus that receives thetransmission signal.
 6. The video transmission method according to claim4, wherein in the generating of the transmission signal, a video signalis generated by coding the first video data and the second video data,and the transmission signal including the first information is generatedby multiplexing the video signal generated and an audio signal.
 7. Thevideo transmission method according to claim 1, wherein the transmissionsignal includes second information indicating the transition period. 8.A video reception method performed by a video reception apparatusincluding a display, the video reception method comprising: receiving areception signal including, in a time series, first video data having afirst luminance dynamic range and second video data having a secondluminance dynamic range wider than the first luminance dynamic range,wherein, in the reception signal, a signal level corresponding to aluminance value is limited to a value lower than a limit value that ispredetermined, in a transition period provided for switching from one ofthe first video data and the second video data to the other, and thereception signal includes first information for notifying, in a firstperiod immediately after a start of the transition period, switching ofa luminance dynamic range, the video reception method furthercomprising: switching the luminance dynamic range of the display duringa switching allowed time that starts when the first information isobtained, the switching allowed time being a length of time allowed forswitching the luminance dynamic range.
 9. The video reception methodaccording to claim 8, wherein the first period is a period of time fromimmediately after the start of the transition period to a time precedinga switching time by the switching allowed time, the switching time beinga time at which the one of the first video data and the second videodata is switched to the other.
 10. The video reception method accordingto claim 8, further comprising: obtaining a video signal and the firstinformation by demultiplexing the reception signal multiplexed from thevideo signal and an audio signal; and obtaining the first video data andthe second video data by decoding the video signal obtained.
 11. Thevideo reception method according to claim 8, wherein the receptionsignal includes second information indicating the transition period. 12.A video transmission apparatus, comprising: a generator that generates atransmission signal including, in a time series, first video data havinga first luminance dynamic range and second video data having a secondluminance dynamic range wider than the first luminance dynamic range;and a transmitter that transmits the transmission signal generated,wherein the generator limits a signal level corresponding to a luminancevalue to a value lower than a limit value that is predetermined, in atransition period provided for switching from one of the first videodata and the second video data to the other.
 13. A video receptionapparatus including a display, the video reception apparatus comprising:a receiver that receives a reception signal including, in a time series,first video data having a first luminance dynamic range and second videodata having a second luminance dynamic range wider than the firstluminance dynamic range, wherein, in the reception signal, a signallevel corresponding to a luminance value is limited to a value lowerthan a limit value that is predetermined, in a transition periodprovided for switching from one of the first video data and the secondvideo data to the other, and the reception signal includes firstinformation for notifying, in a first period immediately after a startof the transition period, switching of a luminance dynamic range, thevideo reception apparatus further comprising: a display controller thatswitches the luminance dynamic range of the display during a switchingallowed time that starts when the first information is obtained, theswitching allowed time being a length of time allowed for switching theluminance dynamic range.